Hydroponic control apparatus

ABSTRACT

A small (e.g. in home) hydroponic installation is controlled by a computer. The computer controls the on/off status of the outputs such as the lights, fan, water pump etc. Corresponding sensors feed data and readings into the computer. The basis operation is carried out by stepping through the outputs and the corresponding sensors. An LCD displays the parameters one at a time, in sequence. A keyboard is provided for entering settings.

This invention relates to hydroponic cultivation, and relates especiallyto the control of the various electrical parameters used in hydroponicinstallations,

BACKGROUND OF THE INVENTION

Hydroponic cultivation of the kind to which the invention relates iscarried out in an indoor Installation, under controlled conditions oftemperature, humidity, and so on. The growing plants are set innutrient-controlled water, and their growth is promoted by electriclights.

Hydroponic cultivation has been considered hitherto to be somewhatunsuitable for the amateur operator. It is not common to find aninstallation in, for example, a domestic house. However, the reason forthis low acceptability of in-home hydroponic installations is not cost,particularly; rather, the problem is perceived to lie more with theamount of attention required of the amateur operator, and with the levelof skill and judgement needed.

Thus, the problem is perceived to be that the amateur will havedifficulty in co-ordinating the thermostats, the light-on-light-offcycle, the carbon dioxide monitor, the nutrient acidity sensor, and allthe rest, on a day-by-day basis.

It is now recognised that amateur operators can perfectly easily acquirethe skills needed to operate an in-home hydroponic facility, providedthe controls of the facility are directed, not by constant manualattention from the operator, but to a large extent by sensors, acomputer, and programmed operational sequences.

The invention lies in a control apparatus which is highly suitable forhousehold or domestic hydroponic installations. The apparatus of theinvention is suitable for in-home installations, not only on operationalgrounds, but also on the grounds of cost, and on the grounds of thelevel of complexity needed for the number of parameters of operationfound in a typical small hydroponic system. Of course, a conventionalcomputer (ie a typical computer of the kind that has eg 1 Mb of RAM,display screen, keyboard, etc) could be programmed to operate thehydroponic facility. However, that would not be desirable: the computerwould have to be dedicated to that use, which would be far tooexpensive. Besides, the amateur may not be familiar with computerprogramming and operation.

In a commercial hydroponic installation, with many growing rooms, withmany employees who are paid to take care of the mundane chores, theeconomics are different, and it is worthwhile to dedicate even expensiveequipment for controlling the process. Thus, sophisticated computerisedcontrol systems are commonly to be found in conventional commercialhydroponic installations.

The invention is aimed at a system which is inexpensive enough that itcan be dedicated for use in an in-home hydroponic facility, and which iseasy to operate even by a person with no knowledge of computerprogramming or operation.

Of course, small, domestic hydroponic installations do exist at present.However, installations of the present designs are invariably controlledto a huge degree not by computers and automatic programs but by theconstant personal attention of the human operator. It is this largeamount of skilled attention required that is perceived as the barrier toin-home hydroponic installations becoming more widespread.

The lights, pumps, control components, etc, of the hydroponicinstallation are all electrical. The conventional practice is to providethe usual several instruments or sensors, eg pH meter, max-minthermometer, and the rest: the operator uses his knowledge and skilledjudgement to adjust the light cycle, the humidity, the CO2 content, etc.In practice, the operator checks the readings and settings, then leavesthe installation for a while; then he keeps coming back, adjusting thecontrols, and again repeating the mundane tasks.

It is recognised that what is required is an all-in-one controllerdevice, with a timer and a computer, to which the operator can plug-inall the sensor inputs, and plug-in all the powered outputs, whereby hecan leave the system, once set, to operate automatically. With the useof the device, the operator can let his settings of the timer and inputsensors do the mundane work, and control the outputs. Equally, relievingthe operator of the mundane operation, and yet ensuring that theoperational steps are carried out systematically and thoroughly, meansthat the operator is now freed to put his knowledge and enthusiasm intothe really interesting part of hydroponic cultivation, namely intotrying out new programs with a view to improving yield, growth speed,etc.

By comparison, conventional amateur horticulture (ie gardening) can be apleasurable hobby even as regards the mundane chores, such as digging,planting, weeding, etc. This is much less true of amateur hydroponiccultivation, in that the mundane chores comprise, mainly, of such thingsas checking thermostats and pushing switches. The interest ofhydroponics, to the amateur, lies more in the experimentation that canbe done, and it is in this area that the invention is useful. Theinvention relieves the operator of the mundane chores, and yet ensuresthat those chores are done consistently. The invention allows theoperator to set and adjust the parameters according to his own ideas,and to know that his settings will be followed automatically, withoutthe need for constant attention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

By way of explanation of the invention, exemplary embodiments of theinvention will now be described with reference to the accompanyingdrawings, in which:

FIG. 1 is a diagrammatic elevation of a hydroponic cultivationoperation, in which the operational parameters are under the control ofa control apparatus which embodies the invention;

FIG. 2 is an elevation of a control box of the apparatus shown in FIG.1;

FIG. 3 is an elevation of a relay box of the apparatus shown in FIG. 1;

FIG. 3A is an elevation of a slave relay box of the apparatus shown inFIG. 1;

FIG. 4 is an elevation of a sensor box of the apparatus shown in FIG. 1;

FIG. 5 is a block diagram of a computer system, which is a component ofthe apparatus shown in FIG. 1.

The apparatuses shown in the accompanying drawings and described beloware examples which embody the invention. It should be noted that thescope of the invention is defined by the accompanying claims, and notnecessarily by specific features of exemplary embodiments.

FIG. 1 shows a hydroponic cultivation operation, of the usual kind, inwhich two rooms A and B are controlled independently as to lighting,temperature, humidity, etc. In room A seeds develop into seedlings, andin room B the seedlings grow into mature plants.

In each room, there are the usual troughs 12 of nutrient-bearing water,with the associated tanks, float-valves, drains, recirculation piping,and other passive (ie not powered) components, (designated collectivelyunder reference numeral 14) and powered by electrical pumps and valves16. Positioned above the troughs are the usual electric lights 18. Thehydroponic system also includes the usual carbon dioxide source 20, andincludes conventional means 23 for correcting the nutrient qualities,pH, etc, of the water in the troughs.

Often, in a domestic installation, the heat from the lights 18 issufficient to keep the rooms warm enough. Often, the rooms can be keptcool enough by the use of a simple air-extraction fan 25. However,heaters, and/or coolers 27, as separate electrical items, may be presentin some cases, especially in areas with extremes of climate. (Hydroponicrooms generally are well insulated thermally.)

Each room is equipped also with the usual (electrical) sensors. Theseinclude an air-temperature sensor 29, a humidity sensor 30, a water-pHsensor 32, a water-EC sensor 34, and a CO2-content sensor 36. The roommay also be equipped with a light sensors 38. All the sensors29,30,32,34,36,38 feed, at least indirectly, into a control box 40.

The control box 40 is fitted with a visual display unit 43, which inthis case comprises a forty-character liquid-crystal display unit ofproprietary design. The control box 40 also is fitted with an inputdevice which permits the operator manually to enter numbers, settings,etc, and which in this case comprises a twelve-key keyboard unit 45.

The control box 40 is also fitted with a clock or timer 47, and acomputer 49.

The signals received from the sensors 29,30,32,34,36,38, from the clock47, and from the keyboard 45, are acted upon by the computer 49. Thecomputer then issues commands to the electrically-powered elements14,16,18,20,23,25,27, whereby the elements are switched on and off atappropriate times and sequences.

The several outputs from the computer are in the form of simple on/offelectrical signals. These signals pass to relays through which power isactually fed to the elements 14,16,18,20,23,25,27. The relays may be ofthe electromechanical type, or of the electronic type.

The relays are housed in a relay box 50. In the relay box (see FIG. 3)the on/off control signals from the computer are transmitted to therelay box through a cable 52; the relay box receives mains power viacable 54; and transmits power to the elements 14,16,18,20,23,25,27, viathe several cables connected to the elements, the on/off settings of therelays being dictated by the outputs from the computer.

In the case of a domestic hydroponic installation, it usually turns outthat all the electrical current needed to power the installation can bederived from a single mains power point, ie the total current draw isless than 15 amps (at 120 VAC). The electric lights account for most ofthis current. In a case where more light, and more amperage, isrequired, ie where the power handling capacity of the relay box 50 maynot be enough to handle the electrical loads, a slave relay box 56 (seeFIG. 3A) can be provided, which is connected in parallel with thelights-circuits in the main relay box 50, and controls the supply ofpower to the extra lights from another 15 amp source.

A sensor box 58 is provided, and the electrical leads from the sensors29,30,32,34,36,38 are arranged to be connected thereto. Those of thesensors which require a (usually, low-voltage DC) power supply are fedfrom an appropriate power supply unit which can be located in the sensorbox.

Some types of sensor may require pre-conditioning of the electricalsignals therefrom (eg matching of impedances, etc) before passing to thecontrol box 40, and this can be carried out in the sensor box 58. Thesignals have to pass through an A-to-D converter in order to beprocessed by the computer 49, and this can be done also inside thesensor box.

Those sensors which monitor conditions in the room generally, such asthe air-temperature sensor 29 and the humidity sensor 30, are houseddirectly in the sensor box 58, and accordingly provision is made for theair in the room to circulate through the sensor box. The light sensor 38also is provided in the sensor box. The pH and EC sensors 32,34 areremote from the sensor box, and are connected thereto by plug-in cables.

The display unit 43, the keyboard 45, and their manner of use, will nowbe described.

In a first manner of operation, the operator enters on the timer thesettings of the various switched output elements 14,16,18,20,23,25,27.That is to say, all the outputs are controlled by the timer. Forexample, not only are the lights 18 set to come on for eighteen hours ofthe day, but the CO2 source 20 is set to admit CO2 for thirty minutesper day. The sensors are not used directly, in this case, to control theoutputs, but rather the system is set to give read-outs of the maximumand minimum values of the sensor signals that occur over the day. Theoperator reviews the max/min readings from the sensors; then, he canadjust the timing of the switched outputs depending on what the readingsindicate. In this first manner of operation, the sensors do not directlycontrol the outputs--the timer does that--but rather the sensors informthe operator whether he should make any changes to the timed sequencesof the output switches.

In order to set the various time sequences and cycles, the operator usesthe keyboard 45 and display 43 to step through the different outputelements. The outputs are programmed to appear on the display in acertain order. Thus, after selecting the Set-Point mode, the operator ispresented with a display which reads Lights On Start Time?. He uses thekeyboard to enter a suitable start time. Having set the lights-on starttime and duration, he is next presented with Number Of Watering CyclesPer Day?, then Start Time Of First Watering?, and Number Of MinutesWatering Pump Is On?, etc. All of these questions are answered by typingin the appropriate numbers from the keyboard.

As mentioned, in this first manner of operation, the timer directlycontrols all the outputs. The sensors are just used for recording andindicating purposes, not for direct control.

In a second manner of operation, the timer again controls some of theoutputs, but others of the outputs are controlled directly by theappropriate sensors. Thus, the operator still sets thelights-on/lights-off cycle by means of the timer; but the fans or otherheat control device are operated not by the timer but by the temperaturesensor 29. In this second manner of operation, as the operator stepsthrough the different outputs, the questions appearing on the displayinclude Maximum Temperature Set-Point? as distinct from straight timingsettings.

In this second manner of operation, the manner in which the sensorsinteract with the outputs is pre-programmed. For example, the unit maybe programmed to link together the fan 25 and the CO2 source 20. The fanruns in order to cool the room; the fan drives the hot, moist air out,and draws relatively cool, dry, fresh air in. After the fan has beenrunning, and the room has cooled, the CO2 content of the room willtherefore have become depleted by the incoming fresh air.

The CO2 sensor determines whether CO2 should be added. If so, thecomputer turns on the CO2 source for a period of, say thirty minutes,and during that time the computer disables the exhaust fan. After 30minutes, the fan is again enabled. If more CO2 is needed, it will beadded in another thirty minute burst, with the fan disabled, next timethe fan is run.

This manner of operating, ie linking the CO2 sensor to the timing of thefan, is often preferable to leaving the CO2 content to be determinedjust by the CO2 sensor alone, since changes in CO2 content can take sometime to be reflected in the CO2 sensor signals.

With the control system as described, the preprogramming required tolink sensors and operations together in this manner can be very easilybe put into effect.

If the operator requires more flexibility, again that can be arrangedusing the step-through system as described. In the third manner ofoperation, as before each output comes up in turn for setting as theoperator steps through the outputs. But in respect of each output, theoperator now steps through each input sensor, whereby he can set thevalues of each sensor to the levels he desires in order to control thatoutput element. For example, he can set the fan to come on when thehumidity rises above eighty-five percent, and he can independently setthe fan to come on when the temperature rises above eighty degrees.

The program determines which sensors or inputs are presented to theoperator in respect of each output. In the first manner of operation,just the timer is presented for setting in respect of each output. Inthe second manner of operation, some of the sensors are programmed tointeract, although the interaction is pre-programmed, and the manner ofinteraction is not under the set-able control of the operator. In thethird manner of operation, virtually any sensor can be used to controlany output, although pre-programming can be used to eliminate obviousnonsense, such as having the temperature controlled by the pH sensor.

These three manners of operation can be pre-programmed into thecomputer, so that any of the pre-programmed manners of operation can becalled up. The operator chooses which manner he wants. If he choosestimer-only, he will be presented with just the timer settings as hesteps through the outputs.

Of course, the three manners of operation as described are justexamples; the factor that permits the easy access to whatever manners ofoperation are programmed into the computer is that the display and thekeyboard are arranged to step through the various outputs, enabling theoperator to set the sensors and other inputs appropriate to that output,by the use of the keyboard. Conversely, it may be regarded that it isthe fact of being able to step through the outputs that makes itworthwhile making available a number of preprogrammed manners ofoperation.

Calibration of the various sensors can be carried out by programming thesystem, again, to step through the various sensors. Generally, forcalibrating, the sensor is placed in two separated conditions. Thecomputer can then interpolate and extrapolate the other points in therange.

The two calibration points may be set in two different modes. In thefirst mode of calibrating say the temperature sensor, the computerassumes what the two conditions will be: thus the display sends first amessage Is Temp Sensor Immersed In Boiling Water? (Y=1/N=0) Upon answer1 the program calibrates that signal from the sensor to read 100 degC.on the display. The freezing point is set in a similar way, and thepoints in between then follow by computer-calculated interpolation.

Alternatively, a second mode of calibrating the temperature sensor wouldbe to use any two temperature reference points. The two points would bederived from a separate thermometer placed adjacent to the sensor (in ahydroponic installation it is usual to provide a back-up thermometer).Now, the display would request, for instance: Is Temp Sensor at FirstSet-Point Temperature? (Y=1/N=0). Upon receiving 1, the next displaywould be Enter First Temperature, which the operator would immediatelydo. Then, some time later (when the temperature had changed), thedisplay would run through the same procedure with respect to the secondtemperature set-point. Again, once the computer has two set points towork from, it can interpolate and extrapolate the other points in therange.

Calibrating the pH sensor can be done in either of the two modes also;that is to say, in the first mode the sensor is immersed in sequence intwo different buffer liquids, the pH of which is pre-determined, andprogrammed-in. In the second mode, a separate independent pH-indicatoris used to determine the two pH set-points.

Both calibration modes can be programmed into the computer, and theoperator can select which mode. In either mode, he proceeds to calibrateall the sensors, again by the simple process of stepping them through,one-at-a-time, using the keyboard and the display.

During routine operation of the hydroponic system, when the operator isnot present, the computer steps through the output elements and theinput sensors in sequence, which may be more or less the same sequenceas that obtaining when the operator was setting the parameters.

Consider, for example, the case where several of the sensors are beingused to turn the fan on/off. The computer, in stepping through theoutput elements, comes periodically to "Fan". Now, whilst remaining on"fan", the computer steps through the appropriate ones of the sensors,ie those of the sensors that the operator entered to be considered bythe computer in determining the on/off status of the fan. The computersteps through these sensors in turn, and changes the fan on/off statusif any one of the sensors so require it.

The computer then moves onto the next output element, leaving the fanoutput in that just-set status. Upon completing the whole cycle of theoutputs, the computer will then return to "fan"; again, the computerwill step through the fan-appropriate sensors, and will update theon/off status.

Of course, there is no need, in hydroponic cultivation, for the computerto complete the cycle through all the output elements and input sensorsrapidly. If the computer steps through a complete cycle every thirtyminutes, that would generally be quite fast enough.

The visual display unit 43 is a forty-character LCD unit. During settingand adjustment by the operator, three things are required in respect ofeach step through the output elements: (1) that the particular outputelement (lights, fan, pump, etc) be identified; (2) that the displayunit show the series of pre-programmed verbal messages (such as lightsOn Time?); and (3) that the display unit show the value of the readingor setting of the sensor, timer, etc. as appropriate. In appropriatecases, the display unit also should identify the sensor.

Five or six digits may be reserved for the reading or setting, anotherthree or four digits for identifying the output element, another threeor four again for identifying the sensor or input, and the remainingdigits remain available for displaying the message.

Only one parameter is displayed on the unit 43 at one time. That is tosay, when the display is showing the temperature setting at which thefan cuts in, the display does not (indeed, cannot) show anything else.

The total number of steps to be carried out in order to step rightthrough the cycle of parameters will vary with each hydroponicinstallation--whether the installation includes heaters/coolers, whetherthe installation has reduced power lighting at some parts of the day,and so on. Typically, there will be between four and eight poweredoutput elements, per room. Typically, there will be between five and tensensors feeding input to the computer, per room, plus the timer. Some ofthe outputs will be under the control, as described, of as many as twoor even three of the input sensors, but mostly each one of the outputswill be controlled by just one of the input sensors. Sometimes, it willbe appropriate for the sensor to display both the current reading orstatus of the sensor, and the setting of the maw/min value or values ofthe sensor, at which the computer will act.

The readings preferably are always displayed sequentially, ie only onereading is displayed at one time. However, sometimes the display willhave enough digits available, especially if the display message is keptshort, for both the current reading and the max/min setting to bedisplayed at the same time, which is a convenience for the operator. Itshould be pointed out that although a larger display unit would permitmore settings to be displayed simultaneously, if the display has morethan about forty characters (digits), the simplicity and economy of thesystem of the invention, as described, would be lost.

In typical small hydroponic installations, therefore, the total numberof parameters is in the region of twenty to thirty. That is to say:stepping through all the output elements, and stepping through all thesensors appropriate to each one of those output elements, will require atotal number of steps in the region of between twenty and thirty.

It is recognised that this is just the sort of manageable number thatcan be handled by the procedure of stepping through. With a largernumber of steps, the operator would start to lose track of where he hasgot to in the stepping sequence and the system becomes generally toocumbersome and unmanageable. With a much smaller number of steps, itwould be as economical to provide separate sensors and elements, eachwith its own display, setting means, etc. In the prior art, for example,a simple thermostat was used to control the fan; one timer was used tocontrol the lights, and another timer was used to control the CO2. Whenthere are twenty or thirty such parameters, however, providing separateequipment for each is wasteful; the invention, by using the same visualdisplay and the same keyboard for each parameter, avoids thisuneconomical duplication.

It is recognised that in small hydroponic installations of the size andtype likely to be selected for in-home use (and even for smallcommercial installations) a highly economical system for controlling theinstallation is to provide just one display unit, just one keyboardunit, and then to step through each output and sensor in turn.

It is also recognised that, by routing all the parameters through theone computer, more interactions can be created between the sensors andthe outputs than when each was a separate entity.

The one-display--one-keyboard--step-through system as described isversatile and flexible as regards accommodating the different controlrequirements of even a creative operator; the system is reliable in thesense that the parameters are reproduced consistently and evenly, onceset, and in the sense that the system should enjoy a long service life;and yet the economics of the system are entirely suitable for smallhydroponic installations.

The apparatus shown in EP-0,142,989 is considered background art to theinvention.

I claim:
 1. Apparatus for controlling hydroponic cultivation,characterized in that the apparatus combines the following features:theapparatus includes several electrical output elements; one of the outputelements is connected, in use of the apparatus to control the operationof a hydroponic cultivation facility, to an electric light unit of thefacility; the apparatus includes several electrical input elements, theinput elements being capable, in use of the apparatus, of receivinginput signals from respective independent sensors; one of the inputelements is so arranged as to receive, in use, an electrical signal froma sensor which senses the temperature of the hydroponic cultivationfacility; the apparatus includes a computer; the apparatus includesmeans for conveying the signals from the sensors into the computer, andthe computer is effective to receive said signals; the apparatusincludes a timer or clock, which is effective to produce electrical timesignals, and the apparatus includes means for conveying the signals fromthe clock into the computer, and the computer is effective to receivesaid signals; the apparatus includes a manual input device, which iseffective to produce electrical signals corresponding to manualmanipulations of the device, and the apparatus includes means forconveying the signals from the manual input device into the computer,and the computer is effective to receive said signals; the apparatusincludes respective control switches, one for each output element, forsetting the on/off status of the respective output elements; thecomputer is effective, in accordance with a pre-determined program, andin response to the signals from the sensors, signals from the clock, andsignals from the manual input device, to operate the control switches,whereby the computer is effective to control independently the on/offstatus of the output elements; the apparatus includes a visual displaymeans; in respect of each output element, at least one of the sensorscorresponds to that output element, and the computer is effective to setthe on/off status of the output element in accordance with the settingof that corresponding sensor; the apparatus includes means for steppingthe display means sequentially through the output elements, and forselecting each output element in turn for display, sequentially, on thedisplay means; the arrangement of the apparatus is such that, as eachelement is selected for display, the display means is effective toidentify the selected element, and is effective to display the settingof the corresponding sensor; the arrangement of the apparatus is suchthat, when the setting of the corresponding sensor is on display, theapparatus is at that time then enabled to allow an operator to manuallyadjust the setting of the corresponding sensor by means of a keyboard.2. Apparatus of claim 1, further characterised in that the visualdisplay means has the capacity to display about forty alpha-numericdigits.
 3. Apparatus of claim 1, further characterized in that:theapparatus has from four to eight output elements, and the apparatus hasfrom five to ten sensor input elements; and at least one of the outputelements has at least two corresponding sensor input elements. 4.Apparatus of claim 1, further characterised in that the total number ofsteps, upon stepping through all the output elements and all thecorresponding sensor input elements, is between twenty and thirty. 5.Apparatus of claim 1, further characterised in that:the apparatusincludes a container, having a panel; the display means and the keyboardare mounted on the panel; the computer is physically integrated into thecontainer; the container is provided with means for effecting respectiveelectrical connections to the several output and input elements. 6.Apparatus of claim 5, further characterised in that the apparatus issuitable for the simultaneous control of two cultivation facilities,being cultivation room A and room B, and the output and input elementsof room A are substantially duplicated, in the container, in respect ofroom B, and the display means and the keyboard are operable in sequencein respect of both room A and room B.